At age 8, our narrator “discovered her purpose in life” after saving the day for a bride about to walk down the aisle. Jane (Katherine Heigl from “Knocked Up” and “Grey’s Anatomy”) grows up to be the best bridesmaid any bride could ever wish for. She saves the twenty-seven ugly dresses she wore for twenty-seven weddings. Believe it or not, this romantic comedy ends with a wedding. Hers. And you’ll never guess what her twenty-seven bridesmaids wear. But first this selfless enabler hopes her beloved boss George (Edward Burns from “She’s The One” and “One Missed Call”) notices her and proposes. Enter her sexy, shallow younger sister (Malin Akerman), who goes after George and gets engaged. And enter newspaper reporter Kevin (James Marsden) who goes after Jane for his article on a serial bridesmaid and gets promoted. Jane is the romantic with no nerve. Kevin is the cynic with no heart who points out the eight-hundred percent mark-up on wedding cake flour. Writer Aline Brosh McKenna, who adapted “The Devil Wears Prada,” and director Anne Fletcher (“Step Up”) serve a slice of mildly amusing, sorta sweet cake. (Bill Stamets)